Don't call trimChats in onChatBoxAdded event. Reduntant because it will be
called after maximization and after being shown.
Add new method getShownChats and don't trim if only one or zero chats are being
shown.
Don't trim chats when in responsive mode.
Don't call trimChats unnecessarily in the render method of the trimmed chats
thingy.
Previously views were only hidden, but not removed. This was an unnecessary
"optimization" which introduced unnecessary complexity.
Problem solved was that closing minimized chats didn't dereference the model
for hidden "normal" chat views, causing an exception to be raised when trying
to log out.
